Behavior problems were investigated in 342 6- to 18-year-old children adopted from psychosocially depriving Russian institutions that provided adequate physical resources but not consistent, responsive caregiving. Results indicated that attention and externalizing problems were the most prevalent types of behavior problems in the sample as a whole. Behavior problem rates increased with age at adoption, such that children adopted at 18 months or older had higher rates than never-institutionalized children but younger-adopted children did not. There was a stronger association between age at adoption and behavior problems during adolescence than at younger ages at assessment. Children adopted from psychosocially depriving institutions had lower behavior problem rates than children adopted from severely depriving Romanian institutions in the 1990s. The implications of these results are that early psychosocial deprivation is associated with behavior problems, children exposed to prolonged early deprivation may be especially vulnerable to the developmental stresses of adolescence, and severe institutional deprivation is associated with a higher percentage of behavior problems after a shorter duration of exposure.